Method of controlling undesirable plant growth



llnited rates This invention relates to a method of controllingundesirable plant growth. More specifically, this invention relates tothe method of controlling undesirable plant growth by applying thereto acompound of the formula wherein R and i l are non-identical substituentsselected from the group consisting of hydrogen, and 2,3-epoxypropoxy,provided that one of said substituents is hydrogen; its monomethylhomologs, wherein the methyl radical is on a -membered ring; itsdimethyl homologs, wherein the methyl radicals are on non-adjacentS-membered rings; and mixtures thereof.

in the compounds represented by the above structural formula, which areutilized in the method of the present invention, one of the substituentsR and R is hydrogen and the other is 2,3-epoxypropoxy. The compoundsdescribed above can have either of two isomeric structural formulae,that is with the hydrogen in the 5- or 6-position. Thus, the twoisomeric compounds represented by the above structural formula are2,3-epoxy-4,7-methano-3a, 4,5,6,7,7a-heXahydro-5-indenyl glycidyl etherand 2,3- epoxy-4,7methano-3a,4,5,6,7,7a hexahydro 6 indenyl glycidylether.

Prior to the present invention many organic and inorganic substanceshave been proposed and used in atte-npts to control undesirable plants.While several of these substances were partially successful, the problemof controlling the vast number of species of undesirable plant lifestill exists. Some of the previously proposed substances are toxic toonly a few species of plant life, while others are excessively toxic andindiscriminantly destroy both desirable and undesirable plant life.Moreover, a great number of the prior substances are ineffective asherbicides, while a number are toxic to animal life. Thus, although manysubstances have heretofore been proposed as herbicides the problem ofthe efiective and selective control of undesirable plant life stillexists.

Therefore, one object of the present invention is the destruction ofundesirable plant life.

Another object of the present invention is to provide a method for thecontrol of undesirable plant life.

Still another object, is to provide a method for the destruction ofgrowing weeds.

These and other objects of the present invention will be readilyapparent from the ensuing description.

The essential active ingredients of the herbicidal compositions used inthe method or" the present invention, described herein, can be readilyprepared, for example, in a three step synthesis from a suitableunsubstituted or alkyl substituted dicyclopentadiene, or mixturethereof, and epichlorohydrin. In the first step, the suitabledicyclopentadiene is treated, for example, as described in Bruson andReiner, J.A.C.S. 67, p. 723 (1945), to produce the correspondingalcohol.

In the second step, the alcohol intermediate is reacted atent PatentedJan. 14, 19%54 ice with epichlorohydrin in the presence of an acidcatalyst, such as aluminum trichloride, sulfuric acid, borontritluoride, boron trifluoride-etherate complex and the like to form thepropylene chlorohydrin ether intermediate, which is treated with analkali metal hydroxide such as sodium hydroxide to yield the glycidylother product. The last step comprises epoxidizing the glycidyl etherproduct with an epoxidizing agent, such as a peracid, or hypochlorousacid.

Suitable dicyclopentadiene reactants for the first step aredicyclopentadiene, its monomethyl homologs, its dimethyl homologswherein the methyl radicals are on non-adjacent S-membered rings, andmixtures thereof. Dicyclopentadiene is readily formed by thedimerization of cyclopentadiene. The monomethyl homologs ofdicyclopentadiene are formed by the adduction of one molecule ofcyclopentadiene and one molecule of methylcyclopentadiene, while thedimethyl homologs are formed by the adduction of two molecules ofmethylcyclopentadiene.

Commercial methylcyclopentadiene is a mixture of position isomers,predominantly l-methylcyclopentadiene and 2-inethylcyclopentadiene,which are not economically separable. For the purposes of thisinvention, it is sufficient to use commercial methylcyclopentadiene.

Upon dimerization of cyclopentadiene and methylcyclopentadiene a mixtureof the suitable reactants specified above are formed, which can be usedwithout separation or can be separated into individual reactants 0rcombinations of reactants. The monomethyl and dimethyl dic'clopentadiene reactants thus formed are isomeric mixtures, which arenot economically separable from their isomers. It should be noted thatfor the purposes of this invention the mixture of isomeric compoundsthus obtained is suitable as the dicyclopentadiene reactant, althoughindividual isomers or combinations thereof can be used with equalsuccess. It should also be noted that methyl radicals, if present,remain in the same position throughout the procedures described hereinand in the diepoxide product. Thus, the dicyclopentadiene reactantlmethyl-4,7-methano-3a,4,7,7a'tetrahydroindene will forml-rnethyl2,3epoxy-4,7methano-hexahydroindanyl glycidyl ether; thedicyclopentadiene reactant 4-methyl-4,7-methano-3a,4,7,7a-tetrahydroindene will form 4-methyl-2,3-epoxy-4,7-methanohexahydroindanyl glycidyl ether; and thedicyclopentadiene reactant 1,5-dimethyl-4,7-methano-3a,4,7,7a-tetrahydroindene will form1,5-dimethyl-2,3epoxy-4,7-metl1anohexahydroindanyl glycidyl ether.

The first step forms the corresponding alcohol or" the dicyolopentadienereactant by hydration of the latter with a suitable hydrating agentaccording to the procedure described in United States Patent No.2,385,788 to Bruson.

Although it has not been shown whether the hydroxy radical appears inthe 5- or 6-position of the hydrated dicyclopentadiene reactant it isbelieved that both position isomers are formed. Therefore, the hydroxyderivative of the starting material will be named herein withoutspecifying the position of the hydroxy radical, since it is understoodthat a mixture of the two position-isomers is intended. Similarly, thederivatives of the hydroxy derivatives will be narned without specifyingthe position of the radical replacing the hydroxy radical. For example,the hydroxy derivative formed from dicyclopentadiene, and designatedhydroxy-4,7-nethano-3a,4,5,6,7,7ahexahydroindene, is understood to be amixture of S-hydroxy- 4,7 methane 3a,4,5,6,7,7a iexahydroindene and6-hydroxy 4,7 methano 3a,4,5,6,7,7a hexahydroindene; while the diepoxideproduced therefrom, designated as 2,3-epoxy-4,7-methanohexahydroindanylglycidyl ether is understood to be a mixture of 2,3-epoxy-4,7-methano- 3hexahydro-S-indanyl glyoidyl ether and 2,3-epoxy-4,7-methanohexahydro--indanyl glyoidyl ether.

In the second step the hydration product of the first step is reactedwith preferably about one-half its molecular equivalent weight ofepichlorohydrin, although other proportions can be successfullyutilized, either with or without an inert solvent. The reaction isaccomplished in the presence of a catalytic amount of an acidic catalystsuch as those previously named. Upon m'ming the reactants and catalyst,with warming if necessary, an exothermic reaction occurs. When theexothermic reaction subsides, the reactants are heated up to about 100C. to insure maximum conversion. The catalyst is removed, for example,by neutralizing with a basic material, such as a salt of a weak acid anda strong base, a base, or a basic clay, followed by filtration of thereaction mixture. Unreacted epichlorohydrin, unreacted hydrationproduct, and solvent, if present, are removed in vacuo, and thecolorless liquid epichlorohydrin reaction product is recovered bydistillation in vacuo. The propylene chlorohyd-rin radical is nextconverted to the glyoidyl radical by treatment of the epichlorohydrinreaction product with at least an equimolecular quantity of an alkalimetal hydroxide, such as sodium hydroxide. Upon separation of the twoliquid phases and distillation in vacuo of the organic phase, thecorresponding 4,7-methano-3a,4,5,6,7, 7a-hexahydroindenyl glycidyl etherproduct is recovered as a colorless mobile liquid.

The corresponding glyoidyl ether product, prepared as above, isepoxidized with at least an equimolecular quantity of epoxidizing agent,which is added slowly with stirring. Suitable epoxid-izing agents arehypochlorous acid and the peracids, such as peracetic acid, performicacid, perbenzoic acid, and the like. The temperature of the reaction iskept low, below about 35 C., to prevent undesirable side reactions.After the reaction is complete, as determined by the peraoid content inthe reaction mixture, the reaction product is Worked up by separatingfrom water, extracting with diethyl ether, drying, and stripping of thediethyl ether. 'The crude diepoxide compound can be used as such in themethod of the present invention, or can be purified by distilling invacuo to recover the isolated compound.

The manner in which the aforesaid compounds can be prepared isillustrated in the following examples. While specific reactants arepresented in any given example, it is understood that there can besubstituted for the polycyclopentadiene reactant any other reactantfalling within the previously described scope of said reactant.

EXAMPLE 1 Preparation of 4,7-14 ethan-3a,4,5 ,6,7, 7a-H exahydroindenyl2-Hydroxy-3-Chl0ropr0pyl Ether Hydroxy 4,7 methano 3a,4,5,6,7,7ahexahydroindene (75 g.; 0.5 mole), prepared as described in Example 1 ofUnited States Patent No. 2,374,173 to Bruson (therein referred to ashydroxy-dihydronordicyclopentadiene), epichlorohydrin (23 g.; 0.25 mole)and toluene (50 ml.) were placed into a 300 ml. three-necked,roundbottom flask fitted with a mechanical stirrer, thermometer, andreflux condenser. Boron trifluoride-etherate complex (approximately 12drops) was added with stirring, and the stirred contents were heated to70 C., at which temperature the reaction became exothermic. Thetemperature was controlled below about 80 C., by means of an ice waterbath until the exothermic reaction subsided. The contents of the flaskwere then heated to 95 C. for 15 minutes. Sodium bicarbonate g.) wasadded, and the contents were again heated to 95 C. for minutes. Thecontents of the flask were filtered and the toluene stripped from thefiltrate by use of an aspirator followed by stripping of the unreactedreactants by distillation in vacuo. The product 4,7-methano-3a,4,5,6,7,7a-hexahydroindenyl 2-hydroxy-3-chloropropyl ether was recovered bydistillation in vacuo as a colorless liquid boiling at 1-28-129 C. at 1mm. of mercury pressure.

EXAMPLE 2 Preparation of 4,7-214 ethane-3 a,4,5 ,6 ,7,7a-Hexahydroindenyl Glycidyl Ether The product of the previous example (38.5g.; 0.16 mole) and toluene (60 ml.) were charged to the flask describedabove, fitted with a mechanical stirrer and thermometer. Sodiumhydroxide (12.7 g.) in 50% aqueous solution was added with stirring. Thecontents of the flask were heated at -100 C. for 3 hours. The organiclayer was separated from the aqueous layer, and washed with an equalamount by volume of water. The organic layer was dried over anhydroussodium sulfate and ether and toluene were distilled therefrom in vacuo.4,7- methano-3a,4,5,6,7,7a-hexahydroindenyl glyoidyl ether was recoveredfrom the residue by distillation in vacuo as a colorless mobile liquidboiling at 108 -1l2 C. at 1.1 mm. of mercury pressure and \having arefractive index of 1.505 at 255 C.

EXAMPLE 3 Preparation of 2,3-Epoxy-4J-P/Iethanohexahydroina'anylGlyciayl Ether A 25 0 ml. three-necked, round-bottom flask fitted with amechanical stirrer, reflux condenser, internal thermorneter, anddropping funnel, was charged with 4,7- methano 3a,4,5,6,7,7 ahexahydroindeny-l glyoidyl ether (50 g.; 0.2 mole) and diethyl ether(approximately 5 ml.). The dropping funnel was charged with 40%peracetic acid solution (50.4 g.; equivalent to 0.26 mol peracid) towhich had previously been added sodium acetate (1.7 g.) to neutralizethe sulfuric acid present in the stock solution. The peracetic acidsolution was added dropwise with stirring, so as to control thetemperature at 2530 C. After 2 hours the peroxide content of thereaction mixture remained constant. The reaction mixture was poured intowater (about 500 cc.), and the organic phase separated therefrom,dissolved in diethyl ether, Washed with aqueous sodium carbonate andwater until the wash water was no lou er acidic, and dried overanhydrous sodium sulfate. The dried etheral solution was filtered freeof drying agent and stripped of solvent in vacuo. The residue wasdistilled in vacuo and 2,3- epoxy-4,7-methanohexahydroindanyl glycidylether was recovered as the fraction -l35 C. at 0.85 mm. of mercurypressure. The product analyzed as follows for 0 H Oxirane OxygenTheoretical, percent 70. 24 8. 16 14. 40 Found, percent 69. 88 8.14 13.80

EXAMPLE 4 Preparation 0 Dimethyl/1ydroxy-4,7-Methan0- 3 (1,4,5 ,6, 7,7a-Hexahydr0indene Preparation of Dimezlzy[-4,7-Pdethan0-3a,4,5,6,7,7a-Hexahydroindenyl Glycidyl Ether Dimethylhydroxy-4,7-rnethano3a,4,5,6,7,7a hexahydroindene (89 g.; 0.5 mole) prepared as in Example 3and epichlorohydrin (23 g.; 0.25 mole) are reacted by the proceduredescribed in Example 1. The propylene chlorohydrin intermediate thusproduced is converted to dimethyl-4,7methano 3a,4,5,6,7,7ahexahydroindenyl glycidyl ether by the dehydrohalogenation procedure ofExample 2. Dimethyl-4,7-methano-3a,4,5,6,7,7a-hexahydroindenyl glycidylether is recovered by distillation in vacuo from the crude residue afterremoval of the solvents.

EXAMPLE 6 Preparation 1 Dim ethyl-2,3-Ep0xy-4,7-Methan0- Hexalzydroindanyl Glycidyl Ether Dimethyl 4,7 methano 3a,4,5,6,7,7ahexahydroindenyl glycidyl ether (43.5 g.; 0.2 mole) is treated withperacetic acid (50.4 g.) by the method of Example 3 to yield dimethyl2,3epoxy-4,7-methanohexahydroindanyl glycidyl ether, which can be usedas such, or can be purifled by distillation in vacuo.

EXAMPLE 7 Preparation of a Mixture of 2,3-Ep0xy-4,7-Zl4e1han0- Hexahydroindanyl Glycidyl Ethers A dicyclopentadiene fraction (150 g.) of95% purity, the impurities consisting essentially of about 3%monomethyldicyclopentadiene and 2% dimethyldicyclopentadiene, is treatedwith aqueous sulfuric acid by the method of Example 4 to yield thehydroxy derivatives, which are reacted with epichlorohydrin (25 g.) bythe method of Example 1, and the product thereof dehydrohalogenated bythe method of Example 2, to yield the corresponding mixture of4,7-methano-3a,4,5,6,7,7a-hexal1ydroinoenyl giyc-idyl others. The lattermixture is epoxidized with peracetic acid by the method of Example 3, toyield a mixture of 2,3-epoXy-4,7-methanohexahydroindanyl glycidylethers.

F or practical use as herbicides, the compounds used in the method ofthis invention are formulated with inert carriers to obtain properconcentrations and to facilitate handling. For example, these compoundscan be formulated into dusts by combining them with such inertsubstances as talcs or clays. The said compounds are particularly suitedto such dust formulations, and dusts containing from 5 to 25 percent byweight of active compound are convenient for use in the field. Thecompounds of this invention, however, are preferably applied as sprays.These can be made as simple solutions by dissolving the compounds inorganic solvents such as xylene, kerosene, or the methylatednaphthalenes. Solvent solutions of these compounds, which ordinarily areliquids at room temperature, are particularly suited to formulation bythis method.

The compounds used in the method of this invention can also beemulsified or suspended in water by the addition of emulsifiers andwetting agents. The formulations of these active her icidal compoundsare either applied directly to the plants to be controlled, or the soilin which the plants are growing can be treated. Substances such as otherpesticides, stabilizers, activators, synergists, spreaders and adhesivescan be added to the formulations if desired. There is no significantdifference in effect from the amount of water or organic solvent fordiluting these compounds providing the same amount of chemical isdistributed evenly over a given area. Such distribution can be obtained,for example, with low -pressure, lowvolume sprays at the rate of aboutgallons of spray per acre.

In applying the compounds, consideration must be given to the nature andstage of growth of the crop, the species of weeds present, the stage ofgrowth of the weeds, environmental factors influencing the rate andvigor of the weed growth, weather conditions at the time of applicationand immediately following, and the dosage to be applied to a given area.Weeds are most susceptible when they are small and growing rapidly.Early application, therefore, results in better control with lesschemical and increased yields because of the early destruction of thecompeting weeds. The larger and older the weeds the higher theconcentration needed to kill them. Summer annuals should be sprayed whenthey are less than 4 inches high. Winter annuals are most easily killedwhile they are still in the rosette stage. Usually weeds growing rapidlyunder optimum conditions are relatively susceptible, whereas thosegrowing under adverse conditions tends to be resistant to the herbicidesprays.

Exemplary of the more important weeds requiring effective control arelambs-quarters, pigweeds, cocklebur, sunflower, mustards, fan feed,yellow star-thistle, wild radish, French weed, crabgrass, yellowfoxtail, ryegrass, chickweed, and white cockle.

The effectiveness of these compounds in small quantities makes themeconomically sound for Weed control on large areas, with a great savingin labor and cost, in addition to corresponding crop increases. Thesecompounds are particularly valuable in weed control because they areharmful to many Weeds but harmless or relatively harmless to somecultivated crops. Minute quantities in contact with plant tissues may beabsorbed and translocated to all parts of the plant, causing strikingchanges in the form and functions and often resulting in their death.The actual amount of compound to be used depends on a variety of factorsbut is influenced primarily by the species of undesirable plant to becontrolled. Thus, while fractions of a pound of actual compound areoften sufiici nt for post-emergence weed control on an acre of corn,seed flax, perennial grass seed crops, pastures or grazing areas(without legumes), wheat, and the like, the particular species of weedsencountered in evergreen and deciduous dormant nursery stock, nurseryconifers, waste areas, woody brush, and the like may require the use ofone or more pounds of compound per acre for good control. Dosageadjustments with the low-volume, lowpressure applications suggested canbe made by changing the nozzle size, nozzle spacing, pressure, ortraveling rate of the spray equipment.

The manner in which the aforesaid compounds can be utilized in themethod of the present invention is illustrated in the followingexamples.

EXAMPLE 8 Preparation of an Emulsifiable Concentrate of 2,3-Epoxy-4,7-Methano-Hexahydroindanyl Glycz'dyl Ether The following concentrateis prepared by mixing the ingredients intimately in the given percentageproportions by weight:

Percent Product of Example 3 25 Antarox A-40O 40 Methanol 35 AnataroxA40O is the trade name under which a nonionic detergent of the aromaticpolyethylene glycol ether type is sold. The above concentrate is dilutedwith water to the desired concentration for use.

EXAMPLE 9 Preparation of an Emnlsz'fiable Concentrate of Dimethyl-2,3-Ep0xy 4,7 Methano-Hexahydroindarzyl Glycz'dyl Ether The followingingredients are mixed thoroughly in the given percentage proportions byweight:

Percent Product of Example 6 59 Xylene l0 Triton X1( 0 5 Kerosene 26Triton X-IOO is the trade name under which an emulsifier of the alkylaryl polyether alcohol type is sold. The above concentrate is dilutedwith water to the desired concentration for use.

7 EXAMPLE 10 Preparation of a Dust From 2,3-Epoxy-4,7-Zllethan0-Hexahydroindanyl Glycia'yl Ether The product of Example 3 (10% byweight) and talc (90% by weight) are combined and ground to the desiredparticle size in a mechanical grinder-blender.

The herbicidal activity of chemical compounds is often demonstrated bythe ability of the chemicals to kill or arrest the growth of tomatoplants or weeds, such as those previously named. These plants arereadily grown and maintained under uniform conditions for experimentalpurposes in greenhouses, and its response to chemicals is very similarto that observed for a wide variety of economically important species ofundesirable plant life in the field.

The herbicidal eifectiveness of the method of this invention, forexample, can be demonstrated in greenhouse experiments on young pottedcrabgrass and foxtail weeds.

The compounds to be tested are formulated into acetonewater solutions.Duplicate paper pots filled with a sand and vermiculite are seeded withcrabgrass and foxtail seeds. The seeds are germinated and the weedsgrown under artificial lighting with irrigation provided by placing theporous pots in a small amount of water in stainless steel trays. Afterthe weeds have reached a suitable size (about 10 days), they are sprayedwith the spray formulations described above at a rate of four poundsactual chemical per acre. Control plants are sprayed with acetone-Watersolution. The weeds are then observed for a week to ten days and injuryrecorded.

In actual experiments carried out as described above, crabgrass andfoxtail weeds treated with formulations of the product of Example 3showed a marked degree of herbicidal injury, While control Weeds treatedwith acetone-water solution showed no injury.

I claim:

1. A method of destroying undesirable plant life which comprisesapplying thereto a herbicidal composition comprising an inert carrierand, in a quantity which is herbicidally toxic to said undesirable plantlife, a compound selected from the group consisting of a compound of theformula wherein R and R are non-identical substituents selected from thegroup consisting of hydrogen and 2,3-eooxypropoxy, provided that one ofsaid snbstituents is hydrogen; its monomethyl homologs, wherein themethyl radical is on a 5- i mbered ring; its dirnethyl homologs, whereinthe methyl radicals are on non-adjacent S-mernbered rings; and mixturesthereof.

2. A method of destroying growing Weeds which comprises contacting saidweeds with a herbicidal composition comprising an inert carrier and, ina quantity which is herbicidally toxic to said weeds, a compoundselected from the group consisting of a compound of the formula H rrrr nwherein R and R are non-identical substituents selected from the groupconsisting of hydrogen and 2,3-epoxypropoxy, provided that one of saidsubstituents is hydrogen; its monomethyl homologs, wherein the methylradical is on a 5-membered ring; its dimethyl homologs, wherein themethyl radicals are on non-adjacent S-membered rings; and mixturesthereof.

3. A method of destroying growing weeds which comprises contacting saidweeds with a herbicidal composition comprising an inert carrier and, ina quantity which is herbicidally toxic to said weeds,2,3-epoxy-4,7-methanohexahydro-S-indanyl glycidyl ether.

4. A method of destroying growing weeds which comprises contacting saidweeds with a herbicidal composition comprising an inert carrier, and ina quantity which is herbicidally toxic to said weeds,2,3-epoxy-4,7-methanohexahydro--indanyl glycidyl ether.

5. A method of destroying growing weeds which comrises contacting saidweeds with a herbicidal composition comprising an inert carrier, and ina quantity which is herbicidally toxic to said weeds, a mixture of theisomers: 2,3epoxy-4,7-methano-hexahydro-S-indanyl glycidyl ether and2,3-epoxy-4,7-metl1ano-hexahydro-6-indanyl glycidyl ether.

References Cited in the file of this patent UNITED STATES PATENTS 3,012,079 Bruson et al. Dec. 5, 1961 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. $117,852 January 14, 1964 Israel JDissen It is hereby certified that error appears in the above numberedpatent requiring correction and that the said Letters Patent should readas corrected below.

Column 1, lines 15 to 20,, the formula should appear as shown belowinstead of as in the patent:

Column 7 lines 44 to 52, the formula should appear as shown belowinstead of as in the patent:

Signed and sealed this 23rd day of June 1964.

SEAL) ttest:

RNEST W, SWIDER EDWARD Jo BRENNER ttesting Officer Commissioner ofPatents

1. A METHOD OF DESTROYING UNDESIRABLE PLANT LIFE WHICH COMPRISESAPPLYING THERETO A HERBICIDAL COMPOSITION COMPRISING AN INERT CARRIERAND, INA QUANTITY WHICH IS HERBICIDALLY TOXIC TO SAID UNDESIRABLE PLANTLIFE, A COMPOUND SELECTED FROM THE GROUP CONSISTING OF A COMPOUND OF THEFORMULA